The goal of this proposed study is to develop a model system for the neuroethological analysis of the physiological mechanisms responsible for the association of functionally-related behavior patterns in time and the mechanisms by which one such set of behaviors is succeeded by another. I propose to use a simple systems approach to the problem by looking at interactions among three types of behavior in the opisthobranch mollusc, Navanax inermis: 1) predatory behavior; 2) male sexual behavior; and 3) female sex behavior. Chronically implanted cuff electrodes will be used to correlate patterns of activity recorded extracellularly from intact nerves in freely-moving animals with the occurrence of indivdual action patterns. Identification of specific neural correlates of individual action patterns would provide physiological support for the ethological concept of the "fixed" action pattern; that is, that each behaviorally identifiable motor pattern represents the output of a particular central motor program; and against the hypothesis of "self-organization" recently proposed for another opisthobranch, Pleurobranchaea (Mpitsos and Cohan 1986). Distinguishing between these hypotheses will be an important step toward understanding how behavior is organized by the nervous system. While neural correlates of individual action patterns have been identified in various opisthobranchs, there has been no demonstration of a one- to-one correspondence between action patterns and patterns of neural activity during a functional sequence of behaviors, such as has been demonstrated for ecdysis in a cricket (Carlson 1977 a,b). Once such a correspondence is established, electrophysiological data can be used for quantitative analysis of the organization of the behavior, how it changes as the animal changes from one type of behavioral activity to another and the role of endogenous neuropeptides in this process. This would provide the opportunity for a physiological or "hardware" analysis of the "rules of order" (Fentress 1980) or software principles which govern spontaneous changes in behavioral activity. Identification of the physiological mechanisms responsible for spontaneous transitions between behavioral activities in such a model system will be an important step toward understanding the way in which the nervous system acts to organize "normal" behavior and the alterations of these processes associated with neurological and mental illnesses.